Dye-ligand affinity systems

Dye-ligands have been considered as one of the important alternatives to na tural counterparts for specific affinity chromatography. Dye-ligands are ab le to bind most types of proteins, in some cases in a remarkably specific m anner. They are commercially available, inexpensive, and can easily be immo bilized, especially on matrices bearing hydroxyl groups. Although dyes are all synthetic in nature, they are still classified as affinity ligands beca use they interact with the active sites of many proteins mimicking the stru cture of the substrates, cofactors, or binding agents for those proteins. A number of textile dyes, known as reactive dyes, have been used for protein purification. Most of these reactive dyes consist of a chromophore (either azo dyes, anthraquinone, or phathalocyanine), linked to a reactive group ( often a mono- or dichlorotriazine ring). The interaction between the dye li gand and proteins can be by complex combination of electrostatic, hydrophob ic, hydrogen bonding. Selection of the supporting matrix is the first impor tant consideration in dye-affinity systems. There are several methods for i mmobilization of dye molecules onto the support matrix, in which usually se veral intermediate steps are followed. Both the adsorption and elution step s should carefully be optimized/designed for a successful separation. Dye-a ffinity systems in the form of spherical sorbents or as affinity membranes have been used in protein separation. (C) 2001 Elsevier Science B.V. All ri ghts reserved.